1. Field of the Invention
This invention relates to dishwashers and in particular to control means for use in controlling the operation of dish-washers.
2. Description of the Prior Art
In the conventional dishwasher, means are provided for washing dishes therein during a treating cycle with a suitable treating liquid. An electric heater may be provided for heating the treating liquid for improved efficiency in the washing of the dishes.
It is further conventional to utilize such electric heaters to heat the air in the dishwasher during the drying cycle to provide facilitated drying of the washed dishes.
One improved dishwasher control is illustrated in U.S. Pat. No. 3,539,153 of Allen L. Wennerberg et al, which patent is owned by the assignee hereof. The control therein includes a switch which is selectively operable to fire an SCR so as to conduct through a pair of resistors. The effect thereof is to de-energize the heater relay for shutting off the heating unit. The control of the heater in this manner is initiated at the beginning of the drain portion of the final rinse cycle. Alternatively, the control may be arranged to prevent the heating unit from ever being turned on such as for use in washing delicate items.
James W. Jacobs, in U.S. Pat. No. 3,635,229, shows a selective heating system for an automatic washing machine having manually operated selector switches connected in electrical series with a dishwasher timer control circuit for determining which of the heaters will be operative during the washing and drying cycles. The control is arranged so as to permit operation of the apparatus for a full cycle without energizing either of the selectively controlled heaters.
In U.S. Pat. No. 3,798,465 of Lauren W. Guth, a control arrangement for a washing machine is shown having a selector which selectively opens the circuit to the heating element during the dry cycle as desired by the user. The dry cycle selector device includes a switch linked by a shaft driven by a control knob so as to make contact with preselected contact points to connect the heater selectively to two different timer control switches for providing different lengths of time in the drying operation. The heater is energized only through the selector switch.